Some days the refrigerator draws Hannah like a magnet. The 23-year-old pulls open the door, gropes for whatever looks interesting and gorges herself. Several times a week Hannah wolfs down mountains of food, more than 6,000 calories in a single day.

Hannah is a binge eater, subject to regular eating attacks and a loss of control over food consumption. In contrast to bulimia sufferers, Hannah makes no effort to counter her caloric intake by vomiting. As a result, she is obese. At five feet, six inches, she weighs 264 pounds.